Atmospheric sampling glow discharge ionization source for the determination of trace organic compounds in ambient air

McLuckey, Scott A.; Glish, Gary L.; Asano, Keiji G.; Grant, B.

doi:10.1021/ac00171a012

Cited by 190 publications

(159 citation statements)

References 29 publications

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“…Ϫ ] Ϸ 0.8 at steady-state. In addition, the positive ion number density is seen to be substantially larger than the negative ion number density, an effect observed experimentally in the ASGDI source [15]. The calculated [P ϩ ] values are also consistent with those predicted and experimentally observed [21] in the HPEC source, which is also recombinationdominated.…”

Section: Functional Dynamicssupporting

confidence: 84%

“…Because a detailed description of an ASGDI source as applied to the detection of trace organics in ambient air has previously been presented [15], only the salient characteristics of the apparatus pertaining to its dynamics will be presented here. The standard configuration, shown schematically in Figure 1, is comprised of a stainless steel, right cylinder (ϳ4 cm diameter) with the ends enclosed by two electrically isolated, stainless steel, circular plates.…”

Section: Basic Operationmentioning

confidence: 99%

“…Our laboratory has developed another ionization technique, atmospheric sampling glow discharge ion-ization (ASGDI), for use in the analysis of trace amounts of organic vapors in ambient air [15]. The ASGDI source is simple and robust, exhibiting a rapid and memoryfree response to gas-phase samples.…”

mentioning

confidence: 99%

“…The effect of instrumental parameters on performance of the ASGDI source in analytical mass spectrometry have been delineated previously [15,16]. However, a rigorous kinetic analysis of the fundamental processes governing its operation has not been made.…”

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confidence: 99%

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Factors influencing the analytical performance of an atmospheric sampling glow discharge ionization source as revealed via ionization dynamics modeling

Goeringer

2003

J. Am. Soc. Mass Spectrom.

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A kinetic model is developed for the dynamic events occurring within an atmospheric sampling glow discharge that affect its performance as an ion source for analytical mass spectrometry. The differential equations incorporate secondary electron generation and thermalization, reagent and analyte ion formation via electron capture and ion-molecule reactions, ion loss via recombination processes, diffusion, and ion-molecule reactions with matrix components, and the sampling and pumping parameters of the source. Because the ion source has a flow-through configuration, the number densities of selected species can be estimated by applying the steady-state assumption. However, understanding of its operation is aided by knowledge of the dynamic behavior, so numerical methods are applied to examine the time dependence of those species as well. As in other plasma ionization sources, the ionization efficiency is essentially determined by the ratio of the relevant ion formation and recombination rates. Although thermal electron and positive reagent ion number densities are comparable, the electron capture/ion-molecule reaction rate coefficient ratio is normally quite large and the ion-electron recombination rate coefficient is about an order of magnitude greater than that for ion-ion recombination. Consequently, the efficiency for negative analyte ion formation via electron capture is generally superior to that for positive analyte ion generation via ion-molecule reaction. However, the efficiency for positive analyte ion formation should be equal to or better than that for negative analyte ions when both ionization processes occur via ion-molecule reaction processes (with comparable rate coefficients), since the negative reagent ion density is considerably less than that for positive reagent ions. Furthermore, the particularly high number densities of thermal electrons and reagent ions leads to a large dynamic range of linear response for the source. Simulation results also suggest that analyte ion number densities might be enhanced by modification of the standard physical and operating parameters of the source. . In these and other applications, a number of methods have been utilized for generation of ions from compounds of interest. Electron ionization (EI) has been employed for formation of positive ions in situations for which air is leaked directly into the mass spectrometer [5,6]. To enhance ionization selectivity over that exhibited by EI, single-and multi-photon ionization techniques have been used for determination of targeted aromatic compounds in automobile exhaust [7][8][9][10]. More widely used approaches for direct sampling are based on atmospheric pressure chemical ionization (APCI) [11] which is capable of making positive or negative ions. APCI is effected by a sequence of electron-and ion-molecule reactions initiated by electrons that are generally produced via either a corona discharge [12] or a ␤-emitter such as 63 Ni [1,13]. Because the equilibrium distribution in such reactions under normal APCI operati...

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Section: Functional Dynamicssupporting

confidence: 84%

Section: Basic Operationmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Factors influencing the analytical performance of an atmospheric sampling glow discharge ionization source as revealed via ionization dynamics modeling

Goeringer

2003

J. Am. Soc. Mass Spectrom.

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“…Compared to the apparatus depicted in Figure 7, the major change of the instrumentation was the replacement of the heated filament by an ASGDI source. The ASGDI source can be used to form either positive or negative reagent ions, but the main motivation for replacing in situ electron ionization with the discharge source is the bright anion beams that can be generated via the discharge for species with relatively high cross sections for electron capture [52]. With the arrangement shown in Figure 8, each ion source is independently controlled and all the ion species are formed outside the ion trap.…”

Section: Ionization Approaches With 3d Ion Trapsmentioning

confidence: 99%

Evolution of instrumentation for the study of gas-phase ion/ion chemistry via mass spectrometry

Xia

McLuckey

2008

J. Am. Soc. Mass Spectrom.

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The scope of gas-phase ion/ion chemistry accessible to mass spectrometry is largely defined by the available tools. Due to the development of novel instrumentation, a wide range of reaction phenomenologies has been noted, many of which have been studied extensively and exploited for analytical applications. This perspective presents the development of mass spectrometry-based instrumentation for the study of the gas-phase ion/ion chemistry in which at least one of the reactants is multiply charged. The instrument evolution is presented within the context of three essential elements required for any ion/ion reaction study: the ionization source(s), the reaction vessel or environment, and the mass analyzer. Ionization source arrangements have included source combinations that allow for reactions between multiply charged ions of one polarity and singly charged ions of opposite polarity, arrangements that enable the study of reactions of multiply charged ions of opposite polarity and, most recently, arrangements that allow for ion formation from more than two ion sources. Gas-phase ion/ion reaction studies have been performed at near atmospheric pressure in flow reactor designs and within electrodynamic ion traps operated in the mTorr range. With ion trap as a reaction vessel, ionization and reaction processes can be independently optimized and ion/ion reactions can be implemented within the context of MS n experiments. Spatial separation of the reaction vessel from the mass analyzer allows for the use of any form of mass analysis in conjunction with ion/ion reactions. Time-of-flight mass analysis, for example, has provided significant improvements in mass analysis figures of merit relative to mass filters and ion traps. The development and evaluation of new tools has clearly been a central activity and contributor to the dramatic advances in the capabilities of mass spectrometry over the past several decades. In this perspective, we relate the evolution of instrumentation for research activities focused on the study and use of ion/ion reactions and offer it as one example of many where progress in an area of science is intimately related to and dependent on the development of instrumentation. It is provided in appreciation for the inspirational example of creativity in instrumentation development [1] provided by Cooks over the years. Electrospray ionization (ESI) [2], among its many contributions, enabled the development of macro-molecule ion/ ion chemistry as a research area. The multiple-charging phenomenon associated with electrospray makes possible the generation of multiply charged reactant ions. This capability leads to the possibility that at least one ion/ion reaction product can retain charge, which makes such a product directly amenable to study with mass spectrometry. In the past two decades, significant progress has been made in understanding and exploring the gas-phase ion/ion chemistry of high mass multiply charged ions. A variety of potential analytical applications have been developed accordingly. Co...

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Microtrap interface for on-line mass spectrometric monitoring of air emissions

et al. 1999

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One of the problems in on‐line mass spectrometric monitoring of air emissions is that whereas organic pollutants are present at trace concentrations (ppm to ppt levels), background gases such as H2O and CO2 may be present at per cent levels. Moisture in particular is a source of serious interference. A sampling interface that eliminates these interferences but allows the continuous introduction of organics into the mass spectrometer is presented. The interface consists of a micro‐sorbent trap (referred to as the microtrap) that selectively traps the organics, and then injects them into the mass spectrometer via rapid thermal desorption with an electric pulse of ∽1 s duration. Continuous (or near‐continuous) monitoring is achieved by making a series of desorptions while the air flows continuously through the system. The applicability of this approach is demonstrated by monitoring the emissions from a catalytic incinerator. Copyright © 1999 John Wiley & Sons, Ltd.

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Atmospheric sampling glow discharge ionization source for the determination of trace organic compounds in ambient air

Cited by 190 publications

References 29 publications

Factors influencing the analytical performance of an atmospheric sampling glow discharge ionization source as revealed via ionization dynamics modeling

Factors influencing the analytical performance of an atmospheric sampling glow discharge ionization source as revealed via ionization dynamics modeling

Evolution of instrumentation for the study of gas-phase ion/ion chemistry via mass spectrometry

Microtrap interface for on-line mass spectrometric monitoring of air emissions

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